While I was writing tests for Gnash's FSCommand implementation, I noticed that when Gnash is running as a plug-in, FSCommand call made by the SWF with string parameter full of symbols (especially '<' and '>') will not reach JavaScript FSCommand handler, while ones with normal string parameter will.

This problem is not specific to FSCommand: generic `getURL()` instruction, built-in plugin function like `GetVariable()`, and scripting API like `ExternalInterface` are very likely to be affected too; though these will need additional testing to confirm.